JP2004137982A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To most effectively utilize inertia effect and pulsation effect in an intake system and exhaust system of an internal combustion engine. <P>SOLUTION: An effective length of an intake passage and an effective length of an exhaust passage are changed by an intake passage shape variable mechanism 33 and an exhaust passage shape variable mechanism 34. In this case, an intake side electromagnetic drive mechanism 30 and an exhaust side electromagnetic drive mechanism 31 perform opening/closing of an intake valve 28 and an exhaust valve 28 at the timing when the inertia effect and the pulsation effect in the intake system and the exhaust system of the internal combustion engine can be most effectively utilized in the effective length of the intake passage and the effective length of the exhaust passage to be changed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine mounted on an automobile or the like, and more particularly to an internal combustion engine provided with a valve operating mechanism for independently controlling the opening and closing timings of intake and exhaust valves.
[Prior art]
[0002]
Conventionally, by changing the length and cross-sectional area of an intake passage in accordance with the engine speed, pressure fluctuations in the intake passage are used to increase suction efficiency in various engine speed regions, thereby improving output. Is known (for example, see Patent Document 1).
[0003]
In other words, since pressure oscillation occurs in the intake passage due to intermittent intake air accompanying the operation of the internal combustion engine, if a positive pressure wave of the pressure waves is introduced into the cylinder at an appropriate timing, the suction Efficiency can be increased. And since the timing of introducing the positive pressure wave into the cylinder can be adjusted by the length of the intake passage, by changing the length of the intake passage according to the change in the operating state of the engine, in various operating regions, The so-called dynamic effect of intake, that is, the inertial effect and the pulsation effect, caused by the above phenomenon can be effectively used to increase the intake efficiency. Note that such a dynamic effect of intake can also be adjusted by changing the sectional area of the intake passage.
[0004]
Conventionally, in this type of apparatus, the opening / closing timing of the intake valve is fixed, and the intake valve is closed at a time later than the piston bottom dead center by a predetermined timing. Under such conditions, even if tuning is performed to increase the dynamic effect of the positive pressure wave as much as possible by adjusting the length or cross-sectional area of the intake passage, the operating state of the internal combustion engine changes with the change in engine speed, for example. Due to the change in the characteristics of the cylinder pressure, the cylinder pressure increases before the intake valve is closed at low revolutions, causing a blowback, and at high revolutions, the cylinder pressure is low, so intake can still be introduced. Since the intake valve would be closed in this state, it was difficult to enhance the dynamic effect of intake over a wide rotation speed range.
[0005]
On the other hand, as a means for improving the suction efficiency when the length and the cross-sectional area of the intake passage are fixed, there is a method of adjusting the opening / closing timing of the intake valve, particularly the closing timing, in accordance with the operating state of the internal combustion engine. According to this method, at least the closing timing of the intake valve is controlled in accordance with the operation state of the internal combustion engine so that the intake valve is closed at the time when the pressure in the cylinder and the pressure in the intake passage immediately before the intake valve become equal. Good. However, in this case, due to the relationship between the length and the cross-sectional area of the intake passage, the tuning state in which the positive pressure wave generated in the intake passage is most effectively used is limited to a specific operating region. In the region, the dynamic effect due to the positive pressure wave is reduced. Therefore, there is a limit in improving the suction efficiency even by adjusting the opening / closing timing of the intake valve.
[0006]
In Patent Document 2, therefore, both the length and the cross-sectional area of the intake passage are adjusted in accordance with the operation state of the internal combustion engine, and the closing timing of the intake valve is controlled in accordance with the adjustment, so that the intake inertia effect is reduced. Further improvements are being made.
[0007]
On the other hand, there is also known a technique for quickly exhausting a combustion chamber using an exhaust pulsation effect by changing the length and cross-sectional area of an exhaust passage according to an operating state (for example, see Patent Documents 3 and 4). Have been.
[0008]
In addition, a technique that combines a mechanism that adjusts both the length and the cross-sectional area of such an exhaust passage in accordance with the operating state of an internal combustion engine with a valve operating mechanism that allows the opening and closing timing of an exhaust valve to be varied (for example, see Patent Document 1) 5) is also known.
[0009]
[Patent Document 1]
JP-A-48-58214
[Patent Document 2]
JP 60-164610 A
[Patent Document 3]
Japanese Utility Model Publication No. 58-49381
[Patent Document 4]
JP-A-11-107789
[Patent Document 5]
JP-A-3-9026
[Problems to be solved by the invention]
[0010]
In an internal combustion engine, when the pressure in the intake passage immediately before the intake valve is higher than the pressure in the exhaust passage immediately after the exhaust valve, the closing timing of the exhaust valve and the opening of the intake valve are increased in order to improve the intake efficiency and promote the exhaust. By adjusting the timing, it is preferable that the intake valve and the exhaust valve be in an overlapped state in which both are opened.
[0011]
However, in the valve mechanism described in Patent Document 2 in which the opening / closing timing of the intake valve is made variable, the opening timing of the intake valve is adjusted in conjunction with the closing timing. Since it cannot be arbitrarily set independently of the closing timing, the intake valve cannot be opened at the above timing, and there is a limit in improving the suction efficiency and promoting the exhaust.
[0012]
Also, in order to enhance the exhaust effect and improve the suction efficiency, the opening timing of the exhaust valve is adjusted so that the exhaust negative pressure waves are synchronized in the overlap state, and the positive pressure waves due to blowdown from other cylinders are generated. It is preferable not to synchronize.
[0013]
However, in the valve mechanism described in Patent Document 5 in which the opening and closing timing of the exhaust valve is made variable, the opening timing of the exhaust valve is adjusted in conjunction with the closing timing, and the opening and closing timing of the exhaust valve is independently controlled. Since it cannot be set arbitrarily, there is a limit in improving the suction efficiency and promoting the exhaust.
[0014]
In view of such circumstances, an object of the present invention is to utilize an inertial effect and a pulsating effect in an intake system and an exhaust system of an internal combustion engine most effectively.
[Means for Solving the Problems]
[0015]
In order to achieve the above object, an internal combustion engine according to the present invention is provided with an intake passage shape variable mechanism for variably controlling an intake passage shape. A valve mechanism for independently controlling the timing is provided, and the shape of the intake passage that is variably controlled and the opening and closing timings of the intake and exhaust valves are controlled in association with each other.
[0016]
In the internal combustion engine configured as described above, the opening timing and the closing timing of the intake and exhaust valves can be arbitrarily set in accordance with the shape of the intake passage that is variably controlled. And the pulsation effect can be used most effectively.
[0017]
According to a second aspect of the present invention, there is provided an internal combustion engine having an exhaust passage shape variable mechanism for variably controlling an exhaust passage shape, wherein the opening and closing timings of the intake and exhaust valves of the cylinder are independently controlled. A valve mechanism is provided to control the exhaust passage shape variably controlled and the opening and closing timings of the intake and exhaust valves in association with each other.
[0018]
In the internal combustion engine configured as described above, the opening timing and the closing timing of the intake and exhaust valves can be arbitrarily set in accordance with the shape of the variably controlled exhaust passage. And the pulsation effect can be used most effectively.
[0019]
According to a third aspect of the present invention, there is provided an internal combustion engine including an intake passage shape variable mechanism for variably controlling an intake passage shape and an exhaust passage shape variable mechanism for variably controlling an exhaust passage shape. A valve operating mechanism that independently controls the opening and closing timings of the intake and exhaust valves is provided, and the variable control of the intake and exhaust passage shapes and the opening and closing timings of the intake and exhaust valves are controlled in association with each other. Features
[0020]
In the internal combustion engine configured as described above, the opening timing and the closing timing of the intake and exhaust valves can be arbitrarily set in accordance with the intake passage shape and the exhaust passage shape that are variably controlled. Inertia and pulsation effects in the system can be most effectively exploited.
BEST MODE FOR CARRYING OUT THE INVENTION
[0021]
Hereinafter, specific embodiments of the internal combustion engine according to the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine according to the present embodiment and an intake and exhaust system thereof. The internal combustion engine 1 shown in FIG. 1 is an in-line four-cylinder four-cycle gasoline engine having four cylinders 21.
[0023]
The internal combustion engine 1 includes a cylinder block 1b in which four cylinders 21 and a cooling water channel 1C are formed, and a cylinder head 1a fixed to an upper portion of the cylinder block 1b.
[0024]
A crankshaft 23, which is an engine output shaft, is rotatably supported by the cylinder block 1b. The crankshaft 23 is connected to a piston 22 slidably mounted in each cylinder 21.
[0025]
Above the piston 22 of each cylinder 21, there is formed a combustion chamber 24 surrounded by the top surface of the piston 22 and the wall surface of the cylinder head 1a. An ignition plug 25 is attached to the cylinder head 1a so as to face the combustion chamber 24. The ignition plug 25 is connected to an igniter 25a for applying a drive current to the ignition plug 25.
[0026]
In the cylinder head 1a, an open end of two intake ports 26 and an open end of two exhaust ports 27 are formed so as to face the combustion chamber 24, and the fuel injection valve is formed such that its injection hole faces the intake port 26. 32 are attached.
[0027]
On the other hand, a variable intake pipe length mechanism 33 is attached to the intake port 26, and a variable exhaust pipe length mechanism 34 is attached to the exhaust port 27.
[0028]
Here, a specific configuration of the intake pipe length variable mechanism 33 and the exhaust pipe length variable mechanism 34 will be described. Since the variable intake pipe length mechanism 33 and the variable exhaust pipe length mechanism 34 have the same configuration, only the variable intake pipe length mechanism 33 will be described as an example. FIG. 2 shows the external appearance of the intake pipe length varying mechanism 33, and FIG. 3 is an exploded view for explaining the structure of the intake pipe length varying device 33.
[0029]
Describing the structure of the variable intake pipe length mechanism, reference numeral 35 in the figure denotes an intake pipe in which, for example, four pipe bodies 36 are connected in parallel in a horizontal direction (a direction perpendicular to the pipe length direction).
[0030]
One end of each of the pipes 36 is connected to an intake port end, and the other end extends in a direction away from the cylinder head 1a. As shown in FIG. 3, the other end of each tube 36 is formed in a fan shape having a downwardly extending circular arc, and each tip is opened downward. At the lower part of the tube 36 opposite to the arc center of the fan-shaped portion 36a, there is formed a coupling seat 36b formed by a peripheral wall that is in line with the opening peripheral wall of the fan-shaped portion 36a.
[0031]
A surge tank 37 is connected to the fan-shaped portion 36a serving as the other end of the intake pipe 35 so as to cover the opening. That is, in the surge tank 37, as shown in FIG. 3, the cross section of the intake pipe 35 in the pipe length direction is formed in a substantially semicircular shape having the same arc as the fan-shaped part 36a, and the upper part is opened. A closed tank 37a is formed.
[0032]
This tank 37a is combined with the other end of the intake pipe 35 so as to form an arc continuously with the fan-shaped part 36 and the coupling seat 36b, and a substantially semi-cylindrical surge chamber is provided at the other end of the intake pipe 35. Has formed.
[0033]
An intake pipe 38 connected to an air cleaner (not shown) is connected to one of the end walls of the tank 37a near the coupling seat 36b, and guides air from the air cleaner to the combustion chamber 24 of the engine through the tank 37a. It is like that.
[0034]
An auxiliary port body 39 is slidably fitted in each fan-shaped portion 36a serving as the other end of the intake pipe 35 so that the effective length of the intake passage can be changed. Specifically, as shown in FIG. 3, the auxiliary port body 39 has four fan-shaped sliding ports which can be inserted into and removed from the sector 36a with reference to the center of the arc of the sector 36a. It is formed from a body 39a. These sliding mouths 39a are arranged in the horizontal direction following the sector 36a.
[0035]
The center side of the sliding opening body 39a penetrates the center of the arc between the surge tank 37 and the fan-shaped portion 36a, and is connected to the outer peripheral portion of the rotating shaft 40 rotatably supported by both end walls. .
[0036]
Thereby, each sliding mouth 39a is supported so as to be able to be inserted and removed in each fan-shaped portion 36a with the rotating shaft 40 as a fulcrum, and utilizes the rotational displacement of the sliding mouth 39a around the rotating shaft 40. Thus, the effective length of the intake passage can be changed.
[0037]
An output shaft (not shown) of, for example, a step motor 41 is connected to the shaft end of the rotating shaft 40, and according to the rotational displacement of each sliding port body 39 a (auxiliary port 39) driven by the step motor 41. The effective length of the intake passage can be varied steplessly.
[0038]
That is, it constitutes a variable mechanism. In this embodiment, the effective length of the intake passage is the shortest suitable for the high-speed operation region of the engine in which most of the auxiliary port body 39 as shown in FIG. 4 is inserted into the fan-shaped portion 36a. Conversely, from the effective length L1, most of the auxiliary port body 39 moves from the fan-shaped portion 36a into the surge tank 37, and becomes the longest effective length suitable for the low-speed operation region of the engine as shown in FIG. It can be changed in the range up to the length L3.
[0039]
The variable intake pipe length mechanism 33 has been described above in detail, but the same applies to the variable exhaust pipe length mechanism 34.
[0040]
On the other hand, an intake valve 28 for opening and closing each open end of the intake port 26 is provided on the cylinder head 1a so as to be able to advance and retreat. Each intake valve 28 is provided with an electromagnetic drive mechanism 30 (hereinafter, referred to as an intake-side electromagnetic drive mechanism 30) that moves the intake valve 28 forward and backward using an electromagnetic force generated when an excitation current is applied. ing.
[0041]
An exhaust valve 29 that opens and closes each open end of the exhaust port 27 is provided on the cylinder head 1a so as to be able to advance and retreat. Each of the exhaust valves 29 is provided with an electromagnetic drive mechanism 31 (hereinafter referred to as an exhaust-side electromagnetic drive mechanism 31) that drives the exhaust valve 29 forward and backward using an electromagnetic force generated when an exciting current is applied. ing.
[0042]
Here, a specific configuration of the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 will be described. Since the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 have the same configuration, only the exhaust-side electromagnetic drive mechanism 31 will be described as an example.
[0043]
FIG. 7 is a cross-sectional view illustrating the configuration of the exhaust-side electromagnetic drive mechanism 31. In FIG. 7, the cylinder head 1a of the internal combustion engine 1 includes a lower head 10 fixed to the upper surface of the cylinder block 1b, and an upper head 11 provided on the upper surface of the lower head 10.
[0044]
An exhaust port 27 corresponding to each cylinder 21 is formed in the lower head 10, and a valve seat 12 for seating a valve body 29 a of an exhaust valve 29 is provided at an opening end of each exhaust port 27 on the combustion chamber 24 side. Is provided.
[0045]
The lower head 10 is formed with a through-hole having a circular cross section from the inner wall surface of each exhaust port 27 to the upper surface of the lower head 10. The through-hole is provided with a valve shaft 29b of an exhaust valve 29 inserted into the through-hole. A cylindrical valve guide 13 that is freely held is inserted.
[0046]
The upper head 11 is provided with a core mounting hole 14 having a circular cross section into which the first core 301 and the second core 302 are fitted. The core mounting hole 14 is located at a position where the axis of the valve guide 13 is the same as that of the valve guide 13. The lower part of the core mounting hole 14 is formed to have a large diameter, and has a small diameter part 14a at the upper part and a large diameter part 14b at the lower part.
[0047]
An annular first core 301 and a second core 302 made of a soft magnetic material are fitted in the small-diameter portion 14a in series in the axial direction with a predetermined gap 303 therebetween. A flange 301a and a flange 302a are formed at an upper end of the first core 301 and a lower end of the second core 302, respectively. The first core 301 is provided from above and the second core 302 is provided from below. 14, the first core 301 and the second core 302 are positioned by the flange 301a and the flange 302a abutting against the edge of the core mounting hole 14, and the gap 303 is maintained at a predetermined distance. It has become.
[0048]
Above the first core 301, a cylindrical upper cap 305 is provided. The upper cap 305 is fixed to an upper portion of the upper head 11 by passing a bolt 304 through a flange portion 305a formed at a lower end thereof. In this case, the lower end of the upper cap 305 including the flange portion 305a is fixed in a state of being in contact with the peripheral edge of the upper surface of the first core 301. As a result, the first core 301 is fixed to the upper head 11. become.
[0049]
On the other hand, a lower cap 307 made of an annular body having an outer diameter substantially the same as that of the large-diameter portion 14b of the core mounting hole 14 is provided below the second core 302. A bolt 306 penetrates through the lower cap 307, and the lower cap 307 is fixed to a downward step surface of the step portion of the small diameter portion 14a and the large diameter portion 14b by the bolt 306.
In this case, the lower cap 307 is fixed while being in contact with the lower peripheral edge of the second core 302, and as a result, the second core 302 is fixed to the upper head 11.
[0050]
A first electromagnetic coil 308 is gripped in a groove formed on the surface of the first core 301 on the gap 302 side, and a groove formed on a surface of the second core 302 on the gap 303 side is formed in the groove. The second electromagnetic coil 309 is held. At this time, the first electromagnetic coil 308 and the second electromagnetic coil 309 are arranged at positions facing each other with the gap 303 therebetween.
[0051]
An armature 311 made of an annular soft magnetic material having an outer diameter smaller than the inner diameter of the 303 is arranged in the 303. A cylindrical armature shaft 310 extending vertically along the axis of the armature 311 is fixed to a hollow portion of the armature 311. The armature shaft 310 has an upper end extending through the hollow portion of the first core 301 to the inside of the upper cap 305 above it, and a lower end passing through the hollow portion of the second core 302 and having a large diameter portion thereunder. 14b, and is held by the first core 301 and the second core 302 so as to be able to advance and retreat in the axial direction.
[0052]
A disc-shaped upper retainer 312 is joined to an upper end of the armature shaft 310 extending into the upper cap 305, and an adjust bolt 313 is screwed into an upper opening of the upper cap 305. An upper spring 314 is interposed between the upper retainer 312 and the adjustment bolt 313. A spring seat 315 having an outer diameter substantially equal to the inner diameter of the upper cap 305 is interposed on the contact surface between the adjust bolt 313 and the upper spring 314.
[0053]
On the other hand, the lower end of the armature shaft 310 extending into the large-diameter portion 14b is in contact with the upper end of the valve shaft 29b of the exhaust valve 29. A disc-shaped lower retainer 29c is joined to the outer periphery of the upper end of the valve shaft 29b. A lower spring 316 is interposed between the lower surface of the lower retainer 29c and the upper surface of the lower head 10.
[0054]
In the exhaust-side electromagnetically driven valve mechanism 31 configured as described above, when no exciting current is applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, the upper spring 314 moves downward with respect to the armature shaft 310. The urging force acts in the direction (ie, the direction in which the exhaust valve 29 is opened), and the urging force from the lower spring 316 to the exhaust valve 29 in the upward direction (ie, the direction in which the exhaust valve 29 is closed). As a result, the armature shaft 310 and the exhaust valve 29 are held in a state in which they contact each other and are elastically supported at a predetermined position, that is, a so-called neutral state.
[0055]
The biasing force of the upper spring 314 and the lower spring 316 is set so that the neutral position of the armature 311 coincides with the intermediate position between the first core 301 and the core 302 in the gap 303. When the neutral position of the armature 311 deviates from the above-described intermediate position due to an initial tolerance, a secular change, or the like, it is possible to adjust the neutral position of the armature 311 with the adjusting bolt 313 so that the neutral position matches the above-described intermediate position. I have.
[0056]
The length of the armature shaft 310 and the valve shaft 29b in the axial direction is such that when the armature 311 is located at an intermediate position of the gap 303, the valve body 29a is in a fully open side displacement end and a fully closed side displacement end. (Hereinafter, referred to as an intermediate position).
[0057]
In the above-described exhaust side electromagnetic drive mechanism 31, when an exciting current is applied to the first electromagnetic coil 308, the armature 311 is placed between the first core 301, the first electromagnetic coil 308, and the armature 311. When an electromagnetic force is generated in the direction of displacing toward the side 301, and an exciting current is applied to the second electromagnetic coil 309, the armature 311 is placed between the second core 302, the second electromagnetic coil 309 and the armature 311. An electromagnetic force is generated in the direction of displacement toward the second core 302.
[0058]
Therefore, in the above-described exhaust-side electromagnetic drive mechanism 31, the excitation current is alternately applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, whereby the armature 311 moves forward and backward, whereby the valve body is moved. 29a is driven to open and close. At this time, the opening / closing timing of the exhaust valve 29 can be controlled by changing the excitation current application timing and the magnitude of the excitation current to the first electromagnetic coil 308 and the second electromagnetic coil 309.
[0059]
An electronic control unit (ECU) 42 for controlling the operation state of the internal combustion engine is provided in the internal combustion engine 1 configured as described above.
[0060]
The ECU 42 is connected to a CPU 43 via a bus, a ROM 44 in which programs, tables (look-up tables, maps), constants, and the like executed by the CPU 43 are stored in advance, and a RAM 45 in which the CPU 43 temporarily stores data as necessary. And a microcomputer including a backup RAM 46 for storing data while the power is turned on and holding the stored data even when the power is turned off, an interface 47 including an AD converter, and the like.
[0061]
The interface 47 is an air flow rate measuring means and is connected to a hot-wire type air flow meter (not shown) arranged in the intake pipe 35, an engine speed sensor 48, and the like, and supplies signals from these sensors to the CPU 43. It is supposed to. The interface 47 is connected to the igniter 25a, the intake-side electromagnetic drive mechanism 30, the exhaust-side electromagnetic drive mechanism 31, the intake pipe length variable mechanism 33, the exhaust pipe length variable mechanism 34, the fuel injection valve 32, and the like. A drive signal is transmitted to these in response to the request.
[0062]
The hot wire air flow meter measures the mass flow rate of the intake air passing through the intake passage and generates Gn representing the same mass flow rate. The engine speed sensor 48 detects the speed of the internal combustion engine 1, generates a signal representing the engine speed NE, and detects the absolute crank angle of each cylinder.
[0063]
Next, the operation of the intake-side electromagnetic drive mechanism 30, the exhaust-side electromagnetic drive mechanism 31, the intake pipe length variable mechanism 33, and the exhaust pipe length variable mechanism 34 configured as described above will be described. The CPU 43 of the ECU 42 repeatedly executes the program shown by the flowchart in FIG. 8 every predetermined time. Therefore, at a predetermined timing, the CPU 43 starts the process from step 100, and in step 105, fetches the engine speed NE and the air flow rate Gn as the engine load from the above-described sensors.
[0064]
Next, the CPU proceeds to step 110, where a map defining the relationship between the engine speed NE and the air flow rate Gn and the intake pipe length shown in FIG. 9 and the actual engine speed NE and the air flow rate Gn captured in step 105 are described. Based on the above, the effective length of the intake passage suitable for the operation region is determined, and a command is given to the auxiliary port body 39.
[0065]
The map used in step 110 is determined so as to obtain the effective length of the intake passage that has the effect of increasing the intake efficiency over the entire operation range of the internal combustion engine.
[0066]
That is, when the ECU 42 determines that the engine is in the high-load and high-speed operation range based on the detection signals from the hot-wire air flow meter and the engine speed sensor 48, the ECU 42 starts the driving of the step motor 41 as shown in FIG. The port body 39 is rotationally displaced and positioned so that most of the port body 39 is inserted into the fan-shaped portion 36a.
[0067]
Then, the effective length of the intake passage is changed to the shortest effective length L1 at which inertia supercharging can be obtained at a high speed. Thereby, a large amount of air is supplied to the combustion chamber 24 via the intake pipe 38, the auxiliary port body 39, the intake pipe 35, and the intake port 26.
[0068]
When the ECU 42 determines from the detection signals from the hot-wire type air flow meter and the engine speed sensor 48 that the engine is in the medium-load / medium-speed rotation operation region, the driving of the step motor 41 is assisted as shown in FIG. The port body 39 is pivotally displaced and positioned so as to protrude into the middle surge tank 37.
[0069]
Then, the effective length of the intake passage is changed to a medium effective length L2 at which inertial supercharging is obtained in the middle rotation range. As a result, inertia supercharging suitable for the medium rotation operation region works, and a large amount of air is supplied to the combustion chamber 24 via the same path as described above.
[0070]
When the engine is determined to be in the low-load and low-speed operation region based on the detection signals from the hot wire air flow meter and the engine speed sensor 48, the driving of the stepping motor 41 causes the auxiliary port member 39 to operate as shown in FIG. Are rotationally displaced and positioned so that most of them protrude into the surge tank 37.
[0071]
Then, the effective length of the intake passage is changed to the longest effective length L3 at which inertial supercharging is obtained in the low rotation speed range. As a result, inertia supercharging suitable for the low-speed operation range operates, and a large amount of air is supplied to the combustion chamber 24 via the same path as described above.
[0072]
Next, the CPU proceeds to step 115, similarly to the intake pipe length variable mechanism 33, the map defining the relationship between the engine speed NE and the air flow rate Gn and the exhaust pipe length shown in FIG. Based on the actual engine speed NE and the air flow rate Gn, an exhaust pipe length suitable for the operation area is determined, and a command is given to an auxiliary port body (not shown) of the exhaust pipe length variable mechanism 34.
[0073]
Next, the CPU proceeds to step 120, and fetches in step 105 the map defining the relationship between the intake pipe length and exhaust pipe length, the engine speed NE, the air flow rate Gn, and the opening / closing timing of the intake / exhaust valve shown in FIG. Based on the actual engine speed NE and the air flow rate Gn, the intake / exhaust valve opening / closing timing VT suitable for the intake pipe length, exhaust pipe length and operating region at that time is determined, and the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive A command is given to the mechanism 31, and the routine proceeds to step 125, and this routine ends.
[0074]
The map used in step 120 described above takes into account the inertial effect in the intake system and the exhaust system of the internal combustion engine, taking into account the change in the cylinder pressure according to the intake pipe length, the exhaust pipe length and the operation area over the entire operation area of the internal combustion engine. In addition, the opening and closing timing of the intake / exhaust valve that can use the pulsation effect most effectively is determined.
[0075]
In other words, since the characteristics of the pressure in the cylinder change with the change in the intake pipe length and the exhaust pipe length, the opening / closing timing VT of the intake / exhaust valve, the engine speed NE, and the air flow rate Gn are determined for each combination of the intake pipe length and the exhaust pipe length. Use a map that defines the relationship.
[0076]
Thus, even if the intake pipe length and the exhaust pipe length change, the intake valve is closed when the pressure in the cylinder becomes equal to the pressure in the intake passage immediately before the intake valve, so that the suction efficiency is improved.
[0077]
Also, as shown in FIG. 12, even if the intake pipe length and the exhaust pipe length change, when the pressure in the intake passage immediately before the intake valve is higher than the pressure in the exhaust passage immediately after the exhaust valve, both the intake valve and the exhaust valve The overlapping state is opened, so that the suction efficiency is improved and the exhaust is promoted.
[0078]
Furthermore, even if the intake pipe length and the exhaust pipe length change, the exhaust valve is opened so that the exhaust negative pressure wave is synchronized in the overlap state and the positive pressure wave due to blowdown from other cylinders is not synchronized. The scavenging effect and the suction supercharging effect can be enhanced.
[0079]
Since the change in the intake pipe length and the exhaust pipe length is slower than the change in the intake and exhaust pipe open / close timing, the open / close timing of the intake / exhaust pipe is gradually changed in accordance with the change in the intake pipe length and the exhaust pipe length as shown in FIG. Thus, the intake and exhaust valves can be opened and closed at the optimal time even during transition when the intake pipe length and the exhaust pipe length change.
[0080]
As described above, according to the above-described embodiment, the intake and exhaust valves are opened and closed at an optimal timing according to the change in the cylinder internal pressure that changes with the change in the intake pipe length and the exhaust pipe length. The inertia effect and the pulsation effect in the exhaust system can be used most effectively.
[0081]
Note that the present invention is not limited to the above embodiment, and various modifications can be adopted within the scope of the present invention. For example, in the above embodiment, both the intake passage shape variable mechanism and the exhaust passage shape variable mechanism are provided, but an internal combustion engine having only one of them may be used.
[0082]
【The invention's effect】
The inertia effect and the pulsation effect in the intake system and the exhaust system of the internal combustion engine can be used most effectively.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of an internal combustion engine according to the present invention.
FIG. 2 is a perspective view showing an appearance of a variable intake pipe length mechanism.
FIG. 3 is an exploded perspective view for explaining a structure of a variable intake pipe length mechanism.
FIG. 4 is a cross-sectional view showing a case where the effective length of the intake passage is set to a length suitable for a high-load, high-speed operation region by a variable intake pipe length mechanism;
FIG. 5 is a cross-sectional view showing a case where the effective length of the intake passage is set to a length suitable for a medium-load / medium-speed rotation operation region by the intake pipe length variable mechanism.
FIG. 6 is a cross-sectional view showing a case where the effective length of the intake passage is set to a length suitable for a low-load low-speed operation region by the intake pipe length variable mechanism.
FIG. 7 is a sectional view showing a configuration of an exhaust-side electromagnetic drive mechanism.
FIG. 8 is a flowchart illustrating a control routine of a variable intake pipe length mechanism, a variable exhaust pipe length mechanism, an intake-side electromagnetic drive mechanism, and an exhaust-side electromagnetic drive mechanism.
FIG. 9 is a map defining a relationship between an engine speed, an air flow rate, and an intake pipe length.
FIG. 10 is a map defining a relationship between an engine speed, an air flow rate, and an exhaust pipe length.
FIG. 11 is a map defining the relationship between the intake pipe length and exhaust pipe length, the engine speed, the air flow rate, and the opening / closing timing of the intake / exhaust valve.
FIG. 12 is a graph showing switching of the opening and closing timings of intake and exhaust valves with changes in intake pipe length and exhaust pipe length, and changes in the pressure in the intake passage and the pressure in the exhaust passage of the internal combustion engine.
FIG. 13 is an explanatory diagram showing a temporal relationship between a change in intake pipe length and exhaust pipe length and a change in opening / closing timing of an intake / exhaust valve.
[Explanation of symbols]
1. Internal combustion engine
26 ... intake port
27… Exhaust port
28 ... intake valve
29… Exhaust valve
30 ... intake side electromagnetic drive mechanism
31 ... Exhaust side electromagnetic drive mechanism
33… Variable intake pipe length mechanism
34… Variable exhaust pipe length mechanism
42 ... ECU
48 ... Engine rotation speed sensor

Claims (3)

In an internal combustion engine having an intake passage shape variable mechanism for variably controlling the intake passage shape, a valve operating mechanism for independently controlling the opening and closing timings of the intake and exhaust valves of the cylinders is provided. The opening timing and the closing timing of the exhaust valve are controlled in association with each other. In an internal combustion engine having an exhaust passage shape variable mechanism for variably controlling the exhaust passage shape, a valve operating mechanism for independently controlling the opening and closing timings of the intake and exhaust valves of the cylinder is provided. The opening timing and the closing timing of the exhaust valve are controlled in association with each other. In an internal combustion engine provided with a variable intake passage shape mechanism for variably controlling the intake passage shape and a variable exhaust passage shape mechanism for variably controlling the exhaust passage shape, the opening and closing timings of the intake and exhaust valves of the cylinders are independently controlled. A valve actuating mechanism is provided, wherein the intake passage shape and the exhaust passage shape that are variably controlled and the opening and closing timings of the intake and exhaust valves are controlled in association with each other.

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